This Small Business Innovation Research Phase I project aims to investigate the feasibility of developing new compounds capable of utilizing common marker gene expression in transformed cells to control the growth and character of cells in living tissue. If successful, the proposed research will provide breakthroughs needed to advance the promising medical uses of recombinant genes. In Phase I of this project, Marker Gene Technologies proposes to establish the feasibility of the technology by preparing new D-luciferin conjugates of common growth regulators, drugs and enzyme inhibitors, for administration to animal cells or bacteria that contain either the firefly luciferase gene (luc) as a gene fusion marker. These new conjugates will provide innovative methods of utilizing this reporter gene system in transformed cells to affect drug delivery and control selected biological properties. In Phase I, the new conjugates will be assayed in vitro and in vivo for their ability to cause specific and localized inhibition or improvement of cell growth and to deliver activated drugs in a cell- or tissue-specific manner, In Phase II, the conjugates will be further tested in a variety of significant medical applications.